John Carmack on Mutable Variables

Re:John Carmack on Mutable Variables by nielsbot on Thursday October 30, 2025 @11:47PM (#45768207)

I use Swift for work. The compiler tell you this. If a mutable variable is never mutated it suggests making it non-mutable. And vice versa.

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Re:John Carmack on Mutable Variables by qmmmur on Friday October 31, 2025 @03:40AM (#45769302)

As will Typescript, at least using Biome to lint it does.

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Re:John Carmack on Mutable Variables by maleldil on Friday October 31, 2025 @11:38AM (#45773283)

eslint has this too: https://eslint.org/docs/latest/rules/prefer-const

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Re:John Carmack on Mutable Variables by nielsbot on Friday October 31, 2025 @01:05PM (#45774260)

My very minor complaint about TypeScript is you use to use `const` which is 2 additional letters.

Seriously though, I do find it slightly difficult to reason about `const` vars in TypeScript because while a `const` variable cannot be reassigned, the value it references can still be mutated. I think TypeScript would benefit from more non-mutable values types... (I know there are some)

Swift has the same problem, in theory, but it's very easy to use a non-mutable value types in Swift (`struct`) so it's mitigated a bit.

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Re:John Carmack on Mutable Variables by bartvk on Friday October 31, 2025 @04:43AM (#45769704)

Yup, it's pretty great. You get into the habit of suspiciously eyeing every variable that's not a constant.

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